linux-kernel - Re: [PATCH v2 4/4] mm, page_owner, debug_pagealloc: save and dump freeing stack trace

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Date:   Tue, 24 Sep 2019 18:24:36 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michal Hocko <mhocko@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v2 4/4] mm, page_owner, debug_pagealloc: save and dump
 freeing stack trace

On Tue, Sep 24, 2019 at 05:15:01PM +0200, Vlastimil Babka wrote:
> On 9/24/19 1:42 PM, Kirill A. Shutemov wrote:
> >> --- a/mm/page_owner.c
> >> +++ b/mm/page_owner.c
> >> @@ -24,6 +24,9 @@ struct page_owner {
> >>  	short last_migrate_reason;
> >>  	gfp_t gfp_mask;
> >>  	depot_stack_handle_t handle;
> >> +#ifdef CONFIG_DEBUG_PAGEALLOC
> >> +	depot_stack_handle_t free_handle;
> >> +#endif
> > 
> > I think it's possible to add space for the second stack handle at runtime:
> > adjust page_owner_ops->size inside the ->need().
> 
> Uh that would complicate the code needlessly? The extra memory overhead
> isn't that much for a scenario that's already a debugging one
> (page_owner), I was more concerned about the cpu overhead, thus the
> static key.

Okay, fair enough.

-- 
 Kirill A. Shutemov